"But when we domesticated the horse and started feeding him grains, he started developing dental problems," Lookingbill said as his forearm disappeared inside the animal's mouth.

Lookingbill is a practitioner of equine dentistry, a horse dentist. And when he sticks his arm inside a steed's head up to the elbow, he is feeling for sharp edges on the teeth.

When he finds one, or more, he'll scrape them away with a file called a "float." Otherwise, the horse will not be able to chew and digest food properly, a condition which leads to other problems, from loss of weight to the way it carries its head.

A wild horse grazing on pasture land all year wouldn't have this problem. The sand and small stones that it would ingest as the natural result of feeding off the ground would wear down the teeth as it chewed.

But a horse that's kept on a diet of feed grains gets none of that natural material. And since a horse's teeth never stop growing, in six or eight months they can become so sharp that they begin cutting the animal's tongue and cheeks.

So twice a year, people like Lookingbill pay a visit, and with the long- handled floats and a heap of patience, file away all those rough edges.

At 6 foot 3, Lookingbill is a John Wayne-sized man. But at 1,400 pounds, the horse named Walk About at the Out Back Farm near Washington, N.J., is, well, bigger. So what happens can only happen with the animal's cooperation.

"Seventy-five percent of this work is being able to get along with the horse," Lookingbill said.

He started by stroking the animal's forehead and speaking its name in gentle tones. While he did that, he watched the animal's eyes. When the pupils returned to normal size after a few minutes, it was a sign that the horse had relaxed and was ready to accept Lookingbill's handling.

Lookingbill could tranquilize the horse, of course, but the animal has a good memory. To do so once would require the use of drugs on subsequent visits. The horse would demand it.

The animal tolerated Lookingbill's probing hand. It even tolerated the float. As Lookingbill scraped the file back and forth across the horse's teeth, it made a rough sawing noise that vibrated through the purebred's entire skeletal frame.

Not that the horse was powerless. The roof over its stall gave it no room to rear up, but the door was open, and its only tether was a strap connected to its bridle that Lookingbill had wrapped loosely over his shoulder. If the horse were determined to burst from the stall, there would be little that Lookingbill could do.

But like most human dental patients, the horse endured the assault. It squirmed a little. A forlorn look actually crossed its face. But it did not seriously resist.

Horse teeth develop other problems besides the sharp edges. Some feeds are composed of a molasses base that, like the plaque that collects on human teeth, needs to be scraped away from time to time.

It's particularly a problem around the animal's four canine teeth. No one knows why horses have canine teeth, which zoologists say are used to rip raw meat. But even though they may not be needed, these evolutionary throwbacks can become infected if not kept clean.

"I guess way back before the flood, they had some need for these teeth," Lookingbill said.

Walk About's lower canines were encrusted with the molasses residue, and Lookingbill tried to use forceps to tear it loose.

Finally, the horse protested. It wagged its muzzle from side to side so Lookingbill could never get a good grip. Lookingbill patted its neck and tried to coax it, but the horse had lost its patience.

That's when Lookingbill brought out a device called an ear twitch.

It's a simple loop of braided material that slips over an ear and attaches to the bridle. But before Lookingbill clipped it fast, he twisted it several times, squeezing the ear.

The effect is a little like someone giving a gentle twist to your arm. There's no real pain, but the pressure will quicken the heart rate and discourage sudden movements.

The ear twitch worked on Walk About. It thwarted the animal's resistance and kept it quiet long enough for Lookingbill to finish the job.

"Most of this work," Lookingbill said, "is feel and listening."

* * *

There was a time, not long ago, when veterinarians used to do the work that people like Lookingbill do now. But with the return of prosperity and the arrival of a presidential equestrian good enough to ride with England's royal family, the popularity of horsemanship has risen.